JPH08281991A - Sublimation type thermal trnasfer recording method and printer using the same - Google Patents

Abstract

PURPOSE: To improve the printing quality of sublimation type thermal transfer recording by incorporating the heating step of heating a thermal transfer film by dividing the part to be heated on a thermal transfer film into a plurality of times per one position. CONSTITUTION: A sublimation type thermal recording printer comprises a thermal head 30 driven by dividing a heating element into four blocks 1 to 4, a control circuit 20 for applying a voltage to the four blocks 1 to 4, and a CPU 10 for giving print data to the circuit 20. A thermal transfer film and the sheet to be thermally transferred are brought into pressure contact with each other via the head 30 and a platen roller. In the case of the pressure contact, the blocks 1 to 4 of the head 30 are sequentially driven twice by the circuit 20 to not only suppress the instantaneous power consumption but also the temperature of the head is not raised more than required, and hence the sheet to be thermally transferred is not thermally damaged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sublimation type thermal transfer recording method and a printer using this method, and more particularly, to a sublimation type thermal transfer recording method in which a color material of the film is adsorbed to a heat transfer sheet by heating the film. Sublimation type thermal transfer printer.

[0002]

2. Description of the Related Art Generally, in a sublimation type thermal transfer printer, three types of thermal transfer films having yellow, magenta and cyan color materials (dye) are used, and data to be printed (not only character data but image data Printing is performed on the heat-transferred sheet by heating each of them.

In this case, a thermal transfer film having a yellow coloring material is first used, and the thermal transfer film is heated according to the data to be printed, thereby printing on the entire surface of the thermal transfer sheet. Next, a thermal transfer film having a magenta coloring material is used, and similarly, printing is performed by heating according to the data to be printed. Finally, a thermal transfer film having a cyan coloring material is used and printing is performed in the same manner. By printing one color at a time in this manner, color printing is realized.

The heat transferable sheet used for printing has a two-layer structure of a synthetic paper layer and a dye adsorption layer (receptive layer).
The receiving layer is made of polyester, for example. That is, the coloring material eluted from the coloring material layer of the thermal transfer film by heating is adsorbed on the surface of the receiving layer to perform printing.

Conventionally, the gradation control technology in the sublimation type thermal transfer recording system includes a method of controlling an applied pulse width, a method of setting a specific applied pulse width as a minimum applied pulse and reproducing a gradation by the number of times of application. is there. In other words, since the heating time corresponds to the gradation of the data to be printed, the gradation is controlled by changing the applied pulse width according to the gradation value or applying the minimum applied pulse the number of times according to the gradation value. Is reproduced.

On the surface of a thermal head used for sublimation type thermal transfer recording, a heating element for one line of printing on a thermal transfer sheet is provided. If the heating element for one line of printing is driven at the time of printing to heat the entire one line of the thermal transfer film at once, the power consumption momentarily increases. Therefore, in order to suppress the power consumption to a low level, it is usual that the heating elements of the thermal head are divided into blocks of equal size, and pulses are sequentially applied to the divided blocks for printing.

This is done as follows.

First, the heating elements (several thousands) in the thermal head are divided into a plurality of blocks. That is,
A plurality of heating elements belong to one block.
In this case, the heating element groups belonging to the divided blocks may be physically clustered on the surface of the thermal head, or the heating elements belonging to each block may be alternately arranged on the surface of the thermal head. .

Next, the same number of pulses respectively corresponding to this block is created. Then, this pulse is applied to the thermal head according to the print data to drive the thermal transfer film. Specifically, the thermal head is driven by a signal obtained by sequentially ANDing the created pulses and print data.

This conventional sublimation type thermal transfer recording system will be described with reference to FIG.

FIG. 4 is a time chart showing the operation when the heating elements in the thermal head are divided into four blocks and each block is heated in sequence. It is assumed that the high-level portion of each waveform in the figure is supplied with the voltage value required to drive the heating element in the thermal head.

As shown in the figure, each pulse E-H
Becomes high level alternatively. That is, when a certain pulse is emitted (at a high level), another pulse is not emitted (at a low level).

In this recording system, the heating element in the thermal head is divided into four blocks 1 to 4, and these blocks 1
Pulses E to H are associated with ~ 4. In other words, the pulse E corresponds to the block 1, the pulse F corresponds to the block 2, the pulse G corresponds to the block 3, and the pulse H corresponds to the block 4.

For example, if the heating element is 6 in the thermal head.
If there are 000 pieces, and divide this into four,
1500 heating elements belong to each block. When the pulse width of each of the pulses E to H is t, the total pulse width of 4 × t is T2 in the figure, and this time T2 is the time required to print one line.
LF before and after the printing time T2 in the figure is a line feed time.

Here, in order to print 64 gradations,
Print data pulse width from t / 64 (minimum width) to 64t
It is necessary to change to / 64 (maximum width). That is,
When the gradation value is “64”, the pulse width of the print data is 64t / 64 = t. Therefore, the pulse width of the print data matches the pulse width in the figure, the voltage applied to the heating element is maximum, and the maximum density of printing is achieved.

On the contrary, when the gradation value is "1", the pulse width of the print data is t / 64. Therefore, the pulse width of the print data becomes the minimum value, the voltage applied to the heating element is the minimum, and the print with the lowest density is obtained.

That is, since the heating element is driven according to the result of the logical product of the pulse of the print data and each pulse in the figure, the energization time of the voltage applied to the heating element is controlled by the pulse width of the print data. Is there.

As described above, the heating elements for one row are not simultaneously driven by the pulse having the pulse width of T2, but
By sequentially driving the heating elements for one row with four pulses E to H having a uniform pulse width, it is possible to prevent momentary increase in power consumption.

[0019]

In the above-mentioned conventional gradation control technique, the amount of heat generated by the thermal head is large because the applied pulse (energization time) becomes long when the density is high. Therefore, when high-density printing is performed, the receiving layer of the heat-transferred sheet melts in a circle (hereinafter referred to as heat damage),
Only that part will lose the gloss of the heat transfer sheet,
There is a drawback that the print quality is degraded.

Regarding the drive control of the thermal head of the thermal transfer printer, there are JP-A-1-2499367, JP-A-2-270572, and JP-A-1-171869, but these also solve the above-mentioned drawbacks. You cannot do it.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object thereof is to provide a sublimation type thermal transfer recording method with better printing quality and a printer using this method.

[0022]

In the sublimation type thermal transfer recording method according to the present invention, a thermal transfer film is divided into M heated portions (M is an integer of 2 or more; the same applies hereinafter) and each heated portion is heated. In the sublimation type thermal transfer recording method, the coloring material of the film is adsorbed to the thermal transfer sheet by heating by heating N times (N is an integer of 2 or more, the same below) per one heated portion. It is characterized by including.

In the sublimation type thermal transfer printer according to the present invention, the thermal transfer film is provided at M positions (M is an integer of 2 or more, and the same applies hereinafter).
Is a sublimation-type thermal transfer printer in which the color material of the film is adsorbed to a heat transfer sheet by dividing the heat transfer sheet into divided parts to be heated. It is characterized in that it includes heating means for heating by dividing it into the above integers (the same applies hereinafter).

[0024]

In the sublimation type thermal transfer recording in which the color material is adsorbed to the heat transfer sheet by dividing the heat transfer film into a plurality of heat portions and heating each of the heat portions, the heat transfer film is divided into a plurality of portions for each heat portion. To heat. Since the heating element is cooled in a plurality of times, the heating element is cooled during the heating rest time, and thermal damage due to heat storage of the heating element does not occur.

[0025]

Next, the present invention will be described with reference to the drawings.

FIG. 2 is a time chart showing the operation of the printer using the sublimation type thermal transfer recording method according to the embodiment of the present invention. The same parts as those in FIG. 4 are designated by the same reference numerals. FIG. 2 shows a waveform in the case where one color is printed on one line by performing four-division printing twice.

That is, in this example, the gradation value of one print data is divided into two, and the print is performed twice.

That is, in the conventional recording method (FIG. 4),
Pulse E corresponding to blocks 1 to 4 for printing one line
The current application time of the applied voltage was changed within the range of each pulse width time from H to H to express multi-gradation. On the other hand, in the present example, the pulses A1 to D1 and the pulses A2 to D2 are made to correspond to the blocks 1 to 4 for the printing of one line, and the gradation values of the print data are made to correspond to 1/2 respectively.

For example, consider a case where the gradation value is "64." In the conventional recording method, since the voltage corresponding to 64 gradations is applied once, each pulse width is t (FIG. 4).
reference).

On the other hand, in the printer of this example, the voltage corresponding to 64 gradations is not applied at once, but pulse A
A voltage corresponding to 32 gradations is applied on the side of 1 to D1 and then a voltage corresponding to 32 gradations is applied on the side of pulses A2 to D2. Therefore, the maximum gradation value “64” is
It is obtained by superimposing the maximum density of the pulses A1 to D1 and the maximum density of the pulses A2 to D2.

In the present example, the pulse whose pulse width is originally t is divided into two as shown in FIG.
The pulse widths of D1 and A2 to D2 are all t / 2. As a result, the sum of all pulse widths (t / 2) × 8 is T1 in the figure.
This time T1 is the time required to print one line.

Here, attention is paid to the thermal transfer film heated by the thermal head as described above. As described above, the entire line of the thermal transfer film is not heated at the same time, but is divided into M heated portions and each divided heated portion is heated. Then, the heated portion is heated N times in one portion, but the heating time per one time,
That is, the pulse width per one time is approximately t / N.

When the gradation value is "32", a voltage having a pulse width corresponding to 16 gradations is applied on the pulse A1 to D1 side, and then a pulse corresponding to 16 gradations on the pulse A2 to D2 side. Apply a voltage of width. That is, the voltage having the pulse width corresponding to 32 gradations is originally applied once, but the voltage having the pulse width corresponding to 16 gradations is applied twice. Even in this case, the total voltage application time that is finally applied is substantially the same as when a voltage having a pulse width corresponding to 16 gradations is applied, and the printing result is also the same.

If the gradation value is an odd value, pulse A
One of the 1 to D1 side and the pulses A2 to D2 side increases the pulse width by one gradation, that is, the voltage application time. It should be noted that the constant voltage and the constant time required to express one gradation here are different depending on the type of the thermal head and the drive circuit, and therefore the optimum value is determined after evaluation.

FIG. 1 is a block diagram showing the construction of the main part of an embodiment of a printer using the sublimation type thermal transfer recording method according to the present invention.

In the figure, the printer of this embodiment includes a thermal head 30 in which a heating element is divided into four blocks 1 to 4 to be driven, and a control circuit 20 for applying a voltage to these four blocks 1 to 4. , And a CPU 10 for giving print data to the control circuit 20.

In this structure, the thermal transfer film and the thermal transfer sheet are pressed against each other between the thermal head 30 and a platen roller (not shown). During this pressure contact, the blocks 1 to 4 of the thermal head 30 are sequentially driven twice by the control circuit 20, so that not only the instantaneous power consumption is suppressed but also the temperature of the thermal head does not rise more than necessary. Therefore, the thermal transfer sheet does not suffer thermal damage.

The relationship between the temperature of the thermal head and the thermal damage of the heat transfer sheet will be described with reference to FIG.

FIG. 3 shows the heat generation state of the thermal head in the printer according to this embodiment. In the figure, the horizontal axis is the time value, the vertical axis is the temperature [° C.], and TD is the temperature at which heat damage occurs.

As shown in the figure, the gradation value is "6".
4 ", the voltage application time becomes E according to the conventional printer (FIG. 4), so that the temperature of the thermal head rises from T0 at the same time as the start of the voltage application, and the temperature becomes Tb at the end of the voltage application. For this reason, the temperature exceeds the temperature TD at which the receiving layer of the thermal transfer sheet is thermally damaged (broken line portion), and the printing quality is deteriorated.

On the other hand, in the printer of this embodiment, the voltage application time corresponding to the pulse E is divided into the time corresponding to the pulse A1 and the time corresponding to the pulse A2 (),
The first voltage application time is A1, and the second voltage application time is A2 (). Therefore, the first voltage application (A
There is a pause time tR from the end of 1) to the start of the second voltage application (A2 ()).

During the rest time tR, the heat generating element is cooled by heat transfer and heat dissipation. Therefore, the heat storage temperature of the thermal head changes as shown by the solid line in the figure.

Therefore, the temperature of the thermal head rises from T0 at the same time when the voltage application is started, but only rises to a temperature Ta lower than the temperature TD at which thermal damage occurs. In this way, since the temperature of the thermal head rises only up to Ta, the gloss of the heat-transferred sheet is not lost due to heat damage, and the print quality is improved.

By the way, in this example, one color printing for one line is performed twice by four-division printing, but it is obvious that four-division printing may be performed more times. However, as the number of times increases, the above-mentioned pause time tR becomes shorter. As a result, the heating element may be heated again before being sufficiently cooled.

It is obvious that the number of divisions may be increased instead of the four-division printing. However, if the number of divisions is increased, the voltage application time for each printing must be lengthened in order to increase the heat generation amount to the required value, and as a result, the time T1 required for printing one line is reduced. Conventional time T
2 (see FIG. 4).

Therefore, as in this example, four-division printing (M
= 4) is performed twice (N = 2) in a divided manner, but in consideration of the characteristics of the thermal head used in the printer, the number M of divided portions of the heated portion of the thermal transfer film and It suffices to appropriately determine the number of times of heating N per heating portion.

In this embodiment, the printer using the sublimation type thermal transfer recording method has been described, but it is obvious that the present invention is not limited to this and can be widely applied to the sublimation type thermal transfer recording method.

The present invention can further have the following aspects in connection with the description of the claims.

(1) Sublimation in which the heating elements included in the thermal transfer head are divided into M groups and driven for each group to heat the M heated portions of the thermal transfer film corresponding to the heating elements of each group. A sublimation-type thermal transfer recording method, which comprises a driving unit that drives the heating elements in groups of N times per group.

(2) The driving means is characterized in that when the driving time corresponding to the gradation value of the data to be printed is t, the driving time for each group is approximately t / N. The sublimation thermal transfer recording method according to the item (1).

(3) The N is 2 and the M is 4
The sublimation type thermal transfer recording method according to the item (2).

(4) The heating elements included in the thermal transfer head are divided into M groups, and each group is driven for a driving time corresponding to the gradation value to be printed. A sublimation type thermal transfer recording method for heating M heated portions, wherein a driving time corresponding to a gradation value to be printed is divided into N substantially evenly, and each group of the heating elements is divided at each divided time. A sublimation type thermal transfer recording method comprising a driving means for driving the.

(5) Sublimation in which the heating elements included in the thermal transfer head are divided into M groups and driven for each group to heat the M heated portions of the thermal transfer film corresponding to the heating elements of each group. A sublimation-type thermal transfer printer, which is a die-type thermal transfer recording method and includes a driving unit that drives the heating elements in groups of N times.

(6) The driving means is characterized in that when the driving time corresponding to the gradation value of the data to be printed is t, the driving time for each group is approximately t / N. A sublimation thermal transfer printer according to item (5).

(7) N is 2 and M is 4
The sublimation type thermal transfer printer according to item (6).

(8) The plurality of heat generating elements included in the thermal transfer head are divided into M groups, and the heat generating elements belonging to each group are driven for a driving time corresponding to the gradation value to be printed. A sublimation type thermal transfer recording method for heating M heated portions of a thermal transfer film corresponding to an element, wherein a driving time corresponding to a gradation value to be printed is divided into N substantially evenly, and each divided time is divided. A sublimation type thermal transfer printer, characterized in that the sublimation type thermal transfer printer includes driving means for driving the heating elements belonging to each of the groups.

[0057]

As described above, according to the present invention, the thermal transfer film is divided into a plurality of heated portions, and each portion to be heated is heated a plurality of times so that the thermal transfer sheet is not damaged. In addition, a glossy image is obtained, and the printing quality is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a printer using a sublimation type thermal transfer recording method according to an embodiment of the present invention.

FIG. 2 is a time chart showing the operation of the printer using the sublimation type thermal transfer recording method according to the embodiment of the present invention.

FIG. 3 is a diagram showing a heat generation state of a thermal head in a printer using a sublimation type thermal transfer recording method according to an embodiment of the present invention.

FIG. 4 is a time chart showing the operation of a printer using a conventional sublimation type thermal transfer recording method.

[Explanation of symbols]

 1, 2, 3, 4 blocks 10 CPU 20 Control circuit 30 Thermal head

Claims (6)

[Claims] 1. A thermal transfer film is divided into M heated portions (M is an integer of 2 or more; the same applies hereinafter) and each heated portion is heated so that the coloring material of the film is adsorbed to a thermal transfer sheet. A sublimation-type thermal transfer recording method, which comprises a heating step of heating N times (N is an integer of 2 or more, the same applies hereinafter) separately for each portion to be heated. 2. The heating step is characterized in that when the heating time corresponding to the gradation value of the data to be printed is t, the heating time per time of the heated portion is approximately t / N. The sublimation thermal transfer recording method according to claim 1. 3. The sublimation thermal transfer recording method according to claim 2, wherein the N is 2 and the M is 4. 4. A thermal transfer film is divided into M heated portions (M is an integer of 2 or more; the same applies hereinafter), and each of the heated portions is heated so that the coloring material of the film is adsorbed to the thermal transfer sheet. A sublimation-type thermal transfer printer, comprising: a heating unit that heats each of the heated portions N times (N is an integer of 2 or more; the same applies hereinafter) in a divided manner. 5. The heating means, when the heating time corresponding to the gradation value of the data to be printed is t, the heating time per heating of the heated portion is approximately t / N. The sublimation thermal transfer printer according to claim 4. 6. The sublimation thermal transfer printer according to claim 5, wherein the N is 2 and the M is 4.